This invention relates generally to optical interfaces for data communication and, more particularly, to the integration of optical elements into existing microelectronic packaging technology. Optical data communications technology has a number of advantages over wire technology. These include bandwidth, data rate and response characteristics superior to those of conventional wire technology. Optical technology is immune to radio frequency interference (RFI) and electromagnetic interference (EMI) issues associated with wire technology.
Accordingly, the use of optical interfaces for data communications is desirable in a variety of applications such as multi-chip modules (MCMs), printed circuit board (PCB) technologies and integrated backplanes. In such systems optoelectronic devices are employed at the point of conversion from light to electronic transmission, and vice-versa. Optoelectronic devices typically comprise semiconductor devices such as light emitting diodes (LEDs), laser diodes, and Vertical Cavity Surface Emitting Laser (VCSEL) array chips, which exist today in gallium arsenide technology and provide a wide variety of applications including optical interconnections of integrated circuits.
An important aspect of optical communication technology is the optical coupling used to communicate optical signals between optoelectronic components, for example, between different circuit boards or between different chips on a circuit board. Typical systems for interconnecting a plurality of optoelectronic devices involve placing a connector on the edge of the circuit board and inserting a pack or bundle into a shelf so that the connector mates with pins on a backplane. Problems associated with this technology include optical fibers left to hang loose between packs and creating a xe2x80x9crat""s nestxe2x80x9d of fibers. Another problem is that optoelectronic alignment is an expensive hand tuning operation. These problems have limited the applicability of optoelectronic technology.
There is therefore a need for packaging solutions that integrate current packaging technology with new optical communications capabilities. It is therefore an object of this invention to provide a structure for integrating optical devices between a module and a circuit board by a means that utilizes current packaging and semiconductor technology.
These and other purposes of the present invention will become more apparent after referring to the following description considered in conjunction with the accompanying drawings.
The purposes and advantages of the present invention have been achieved by providing, according to a first aspect of the invention an apparatus for integrating optical devices between a module and a circuit board comprising:
a carrier having a plurality of optical waveguides;
a module having a plurality of first optical ports on a bottom surface of the module, the bottom surface of the module connected to the carrier such that the optical waveguides are in communication with the first optical ports; and a board having a plurality of second optical ports on a top surface of the board, the top surface of the board connected to the carrier such that the optical waveguides are in communication with the second optical ports.
The carrier may be a plastic, laminate or a ceramic carrier. The carrier may also have at least one level of metal interconnect capability. In one embodiment the carrier is an interlocking carrier assembly comprised of a first carrier having a plurality of optical waveguides connected to a second carrier having a plurality of electrical connections. The first and second optical ports on the module or board are discrete optical devices such as vertical cavity surface emitting lasers or the end of a corresponding waveguide or optical fiber.
The apparatus may further comprise a plurality of first electrical ports on the bottom surface of the module;
a plurality of second electrical ports on the top surface of the board;
a plurality of electrical connections on the carrier wherein the plurality of first and second electrical ports are in electrical contact with the plurality of electrical connections. The plurality of optical waveguides and the plurality of electrical connections may be arrayed in a variety of patterns including an interstitial pattern or arrayed in a perimeter pattern.
According to another aspect of the invention, there is provided an apparatus for integrating optical devices between a module and a circuit board comprising:
a carrier having a first plurality of optical waveguides and a second plurality of optical waveguides;
a module having a plurality of first optical ports on a bottom surface of the module and a plurality of clearance holes, the bottom surface of the module connected to the carrier such that the first plurality of optical waveguides are in communication with the first optical ports and the second plurality of optical waveguides pass through the plurality of clearance holes;
a board having a plurality of second optical ports on a top surface of the board, the top surface of the board connected to the carrier such that the first plurality of optical waveguides and the second plurality of optical waveguides are in communication with the second optical ports, and
at least one integrated circuit chip having at least one third optical port, the chip attached to a top surface of the module such that the third optical port is in communication with the second plurality of optical waveguides.
The apparatus may further comprise:
a plurality of first electrical ports on the bottom surface of the module;
a plurality of second electrical ports on the top surface of the board;
a plurality of electrical connections on the carrier wherein the plurality of first and second electrical ports are in electrical contact with the plurality of electrical connections.
According to another aspect of the invention there is provided an apparatus for integrating optical devices between a module and a circuit board comprising:
a carrier having a plurality of optical waveguides;
a module having a plurality of first optical ports on a bottom surface of the module, the bottom surface of the module connected to the carrier such that the plurality of optical waveguides are in communication with the first optical ports;
a board having a plurality of second optical ports on a top surface of the board, the top surface of the board connected to the carrier such that the plurality of optical waveguides are in communication with the second optical ports, and
at least one integrated circuit chip having at least one third optical port, the chip attached to the bottom surface of the module, preferably by wirebond, such that the third optical port is in communication with the plurality of optical waveguides.
The apparatus may further comprise:
a plurality of first electrical ports on the bottom surface of the module;
a plurality of second electrical ports on the top surface of the board;
a plurality of electrical connections on the carrier wherein the plurality of first and second electrical ports are in electrical contact with the plurality of electrical connections.